2. A Brief Introduction to Basic Principles of Canadian Constitutional Law

The primary document of the Canadian constitution is the British North America Act
1867, 30 & 31 Victoria, c. 3 (B.N.A. Act). That act together with its
amendments, was and still is, an enactment of the Imperial Parliament of the United
Kingdom. Among other things, the B.N.A. Act provides for a division of legislative
powers between the federal and provincial governments  section 91 lists the
exclusive heads of federal legislative power and section 92 lists the exclusive heads of
provincial power. To determine a statute's constitutional validity, a court must establish
whether or not the legislation is within the power of the enacting government. If the
legislation is within the enacting body's constitutional competence, it is valid or
intra vires and if it is beyond the enacting body's authority it is invalid or ultra
vires.

In interpreting the B.N.A. Act, the court attempts to prevent either level of
government from encroaching on the power of the other. There is in practice, if not in
strict legal theory, however, a presumption of constitutional validity. In effect the
court begins its inquiry by presuming the statute in question to be valid. The burden of
proving otherwise is, therefore, on the party alleging invalidity. Where proper and
possible the court will interpret an enactment in such a way as to make it valid. For
example, if there are two alternative interpretations of an enactment, the court will
adopt the one that brings it within the constitutional competence of the enacting body.1

Basically the courts have adopted a three-step procedure for determining the validity
of a statute. First the court identifies the statute's dominant feature or
"matter" based primarily on its wording, purpose, effect, context, and
legislative history. Merely reading a statute may not provide a true understanding of its
matter. The term "colourability" is used to describe a situation in which the
statute's language disguises its real nature. While the legislation appears valid, careful
analysis indicates that its true matter falls within a head of power reserved for the
other level of government. In such cases the doctrine of colourability is invoked and the
legislation is held to be ultra vires.2

Once the court has determined the subject matter of the legislation, it must then
define the scope of the relevant heads of power in sections 91 and 92. Since the sections
are intended to provide an exclusive set of legislative powers and also overlap, they must
be read contemporaneously. The scope of any head of power is limited by the scope of the
others. This approach to interpreting sections 91 and 92 is referred to as the principle
of "mutual modification."

The heads of power are not defined, but rather are briefly described in broad, general
terms. The ambit of a particular power must be pieced together from the judgments in
various cases. Unfortunately, few cases raising constitutional issues concerning cannabis
have been litigated. Even in areas where there is some relevant caselaw, the courts have
tended to base their decisions on narrow technical grounds which do not permit the
extraction of fundamental principles.

The final step in the process is to determine which head of power the subject matter of
a statute comes within. An enactment may incidentally effect a particular power without
coming within it. This "ancillary" doctrine applies where the encroachment on
the jurisdiction of the other level of government is necessarily incidental to the
effective operation of the legislation in question. For example, a provincial statute may
incidentally affect the federal power of banking s. 91(l5) but its matter may be within
"property and civil rights" s. 92(l3).3 If the encroachment is not
merely incidental, the legislation is said to be "trenching" on the power of
other level of government and is ultra vires.

The power to legislate on a complex phenomenon such as non-medical drug use is unlikely
to be exclusively federal or provincial. While some drug laws may fall exclusively within
either federal or provincial jurisdiction, others may be within the legislative competence
of both levels of government. There is concurrent responsibility for such legislation, and
both levels of government could enact it. As we shall later discuss cannabis prohibition
legislation may well be an example  the provinces could claim that a provincial
prohibition was within their power over public health s. 92(16) and the federal government
could justify their prohibition as a matter of criminal law s. 9(27). In such situations
the law is said to have a "double aspect." In a classic statement of this
doctrine, the court explained, "subjects which in one aspect and for one purpose fall
within sect. 92, may in another aspect and for another purpose fall within sect. 9l."4
If Parliament and the provinces enacted cannabis prohibitions that were incompatible, the
resulting conflicts would be resolved by the doctrines of "paramountcy" and
"concurrency"  these principles will be examined later in the text.

Constitutional analysis is a speculative undertaking. Since legislation is given legal
effect until it has been successfully challenged,5 constitutionally-suspect
enactments may remain operative simply because other governments and private litigants
have no interest in questioning them. Even if the legislation is challenged, predicting
the outcome of constitutional litigation is difficult. While some boundaries of the
federal and provincial legislative domain can be readily identified, many constitutional
issues central to cannabis control are, and will likely remain, contentious.